Energy storage apparatuses that house non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, are widely used as a main or auxiliary electrical power source for vehicles such as gasoline-powered automobiles (for example, see Japanese Unexamined Patent Application Publication No. 2007-195311). Such energy storage apparatuses include those that house a plurality of battery cells hermetically sealed in an outer housing.
When non-aqueous electrolyte secondary batteries malfunction, such as when they are overcharged or internally short circuit, a gas discharge valve (safety valve) provided on the battery cell opens and gas discharges from the safety valve into the interior of the outer housing. The energy storage apparatus includes a discharge port for discharging this gas out of the outer housing.